U.S. Pat. No. 4,424,833 (Spector et al.) discloses a catheter introducer having a self-sealing gasket adapted to maintain a seal and prevent back bleeding both when the catheter is in place through the introducer as well as when the catheter is removed. The Spector et al. device also includes a side entry port through which liquids may be introduced or through which the device may be aspirated. The device is effective to provide a self-sealing gasket that maintains its seal over a relatively wide range of pressures to include not only the normal positive pressure of the patient's blood but also the reduced pressure which results from aspirations through the side port. The device also displays the desirable feature that its self-sealing function is achieved without unduly inhibiting axial and rotary movement of the catheter as it passes through the seal.
Although the foregoing device maintains an effective seal with a catheter passing through it as well as when the catheter is not present, it is somewhat limited in the range of diameters of devices that can be passed through it while maintaining a seal. In particular, guidewires, which typically are used in association with catheters, are of significantly smaller diameter than the catheters and when passed through the gasket, do not maintain an effective seal with the gasket. The guidewires, however, are sufficiently large to break the seal which permits blood to leak out of the proximal end of the device. Therefore, it would be desirable to provide a device having a self-sealing structure that is effective to provide a seal when a catheter as well as when a guidewire extends through the introducer. Moreover, such a device also should be effective to maintain the seal when neither the guidewire nor catheter are in place as well as during aspiration and over a relatively wide range of pressures. Further, such a device should not unduly inhibit axial as well as rotary movement of the catheter or the guidewire. It is among the general objects of the invention to provide such an improved gasketed introducer.